895
FXUS62 KGSP 162339
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
739 PM EDT Thu May 16 2024

.SYNOPSIS...
Brief high pressure moves off the coast tonight as another low
pressure approaches from the west.  Showers and scattered
thunderstorms return Friday and continue into the weekend. Isolated
afternoon and evening showers and thunderstorms are expected early
next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
700 PM Update...No sigfnt changes made to the fcst this evening.
Spotty small-scale showers will continue across the NW Piedmont,
otherwise all other locales will remain dry.

As of 200 pm EDT Thursday: Heights will fall across the region
tonight as a short wave ridge progresses east of the area late
tonight and a low-amplitude short wave trough approaches from the
southwest late Friday morning. Moisture and lift will increase
across the CWA by afternoon, increasing shower chances, with precip
chances becoming likely across western areas by 00Z Saturday.
Mid/high level cloud cover overspreading the area during the morning
will limit the destabilization potential tomorrow afternoon, while
mid-level lapse rates are expected to be very poor. As such, sbCAPE
is expected to generally be limited to the 500-1000 J/kg range.
Thus, while shear parameters (esp deep layer shear) will be
improving throughout the day, the expected shear/buoyancy
combination should preclude a notable severe storm threat. Indeed,
SPC has removed our CWA from the Day 2 Marginal Risk. With
precipitable waters expected to surge above 1.5", There may be a
slightly higher potential for locally excessive rainfall, but
again...limited instability and modest forcing should act to tame
rainfall rates. Min temps tonight will again above normal, while
maxes Friday should be right around climo.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 1245 PM EDT Thursday: Short Term Key Messages

1) Widespread Showers and thunderstorms are expected off and on
throughout the weekend.

2) Areas of heavy rainfall may lead to isolated flooding issues
this weekend.

3) Isolated strong to severe storms are possible through the weekend
but confidence remains low at this time.

Showers and thunderstorms will be ongoing across the western
Carolinas and northeast Georgia Friday evening into Friday night as
a low pressure system approaches out of the west. There may be a
lull in activity the first half of Saturday before another round of
showers and thunderstorms returns Saturday afternoon into Saturday
night as the low pressure system tracks into the forecast area. Have
likely to categorical PoPs (70% to 80%) in place during this
timeframe as global models and high-res models agree that there will
be multiple rounds of convection. All global models continue to
agree that the low will stall over the area on Sunday, thus
monotoned likely PoPs (60 to 70%) across the forecast area. With
PWATs expected to climb near or above 90th percentile, locally heavy
rainfall will be a concern, especially with wet antecedent
conditions already in place. The WPC Day 3 Excessive Rainfall
Outlook has a Marginal risk across the Carolinas as isolated flash
flooding will be possible, especially for areas that saw heavy
rainfall the day prior. The flooding threat will steadily increase
throughout the weekend as rainfall totals pile up. Currently 0.50-
1.50 inches of rain is expected to fall Friday night through Sunday,
with the highest amounts expected to fall across the western and
southern zones. Isolated strong to severe storms continue to look
possible thoughout the weekend but confidence on this is low as
thick cloud cover may limit destabilization. GEFS plumes show less
than 1,000 J/kg of SBCAPE through the weekend, with ~35-45 kts of
deep shear on Saturday and only ~15-20 kts of deep shear on Sunday.
Thus, Saturday still looks to have the better severe potential, and
this matches up with the Day 3 SPC Severe Weather Outlook which has
a Marginal risk in place east of the mountains. The main potential
hazards with any severe storms that develop are damaging wind gusts
and large hail. High temperatures have trended down slightly for the
weekend and are now expected to be a few to several degrees below
climo. Low temperatures will remain several degrees above climo
thanks to both cloud cover and precip.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 100 PM EDT Thursday: The low pressure system will linger over
the eastern Carolinas through Monday before gradually pushing
offshore Monday evening into Monday night. Thus, maintained chance
PoPs (15% to 30%) across much of the forecast area Sunday night into
Monday. Upper ridging and sfc high pressure will build into the
southeast Monday night into Tuesday night, leading to drier
conditions, while the low pressure system lingers just off the
Southeast Coast. A cold front will approach out of the west on
Wednesday before tracking across the forecast area Wednesday night
into early Thursday morning. This will allow shower and thunderstorm
chances to return towards the end of the forecast period. High
temperatures will remain a few to several degrees below climo on
Monday, becoming near climo to a few degrees above climo on Tuesday.
Highs are then expected to become a few to several degrees above
climo Wednesday into Thursday. Low temperatures will generally
remain a few to several degrees above climo through the period, with
the exception Monday night as lows east of the mtns will be near or
just below climo.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: The overnight period has trended a little
drier with the pattern so now have MVFR CIGs at KAVL and KHKY. An
uptick in convec activity is in store Fri as an upper disturbance
crosses from the southwest. Have PROB30 mention of TSRA at all sites
during the afternoon, persisting until 00z. Expect a transition to
SHRA for the late period at KCLT. CIGS and VSBY remain generally VFR
outside heavier rain showers, but a notable increase in MVFR CIGs
seems likely at KAND aft 22z. Winds remain light overnight and
become aligned s/ly to sw/ly aft 14z-15z across all sites.

Outlook: Periods of convection, which could be widespread at times,
are expected through the weekend. Late night/early morning
restrictions in low stratus and/or fog will also be possible. Drier
weather is expected to return early in the next work week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL/SBK
SHORT TERM...AR
LONG TERM...AR
AVIATION...SBK